热带假丝酵母菌处理马铃薯淀粉废水工艺优化

利用微生物发酵技术,通过正交试验研究了温度、pH值、发酵时间、接种量等因素对热带假丝酵母茵处理马铃薯淀粉废水的影响。结果表明,在温度为28℃、pH值为5．5、发酵时间为28h、接种量为10％的条件下,废水处理效果和热带假丝酵母茵生长情况最佳,且经处理后废水CODCr、色度去除率分别可达到76．0％、73．5％、77．1％．同时可获得9．53g／L的单细胞蛋白。     

Enzymatic ring-opening polymerization of ε-caprolactone by a new lipase from Yarrowia lipolytica

A new lipase from the yeast Yarrowia lipolytica was isolated and used in the enzymatic ring-opening polymerization of lactones. The effect of used commercial oil from a vacuum pump (instead of olive oil) and in the presence of wheat flour was evaluated. It was found that lipase production is favored when wheat flour and used commercial oil is added instead of olive oil with an incubation time of 16.5 h at 29°C and 250 rpm. Lipase shows a specific activity of 3.47 nmoles of 4-methyl umbelliferone released/mg of protein/min. In this way, preculture step can be avoided and an important reduction in production time can be obtained. In vitro polymerization of ε-caprolactone at different temperatures in the presence of n-heptane for 15 days produces low-molecular-weight polyesters with unique multiphase morphology. Polyesters were characterized by NMR (solution and solid-state) spectroscopy, differential scanning calorimetry (DSC), Fourier-transformed infrared, wide-angle X-ray scattering and MALDI-TOF. Polyester crystallinities calculated by DSC were high, as expected for low-molecular-weight PCLs. Final polymer possesses carboxylic acid and hydroxyl end-groups, as determined by ¹H- and ¹³C NMR analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

A comprehensive study of lipase production by Yarrowia lipolytica CECT 1240 (ATCC 18942): from shake flask to continuous bioreactor

BACKGROUND: Lipases are commercially important enzymes, and the development and optimization of their production processes are of great interest. The diversity of behaviours between strains stresses the need for research on this topic, especially when bioreactor culture is considered. The study of a continuous operating mode is especially attractive, since very scarce information is available on its application to microbial lipases production. RESULTS: Lipase production in submerged cultures of Yarrowia lipolytica CECT 1240 (ATCC 18 942) has been investigated. Significant lipolytic activity (over 700 U dm^?3), mostly extracellular and membrane‐bound, was obtained in shake flasks using medium supplemented with olive oil. The culture was carried out in air‐lift and stirred tank bench‐scale bioreactors and the latter was selected. The influence of aeration and agitation rates was assessed in batch cultures, and agitation from 400–700 rpm and low aeration rates (i.e. 0.2 vvm) are recommended. Batch, fed‐batch and continuous operation were investigated, and regular enzyme production (up to 600 U dm^?3) was achieved with the latter. CONCLUSION: Lipase production by the selected strain was successfully carried out in shake flasks and bench‐scale bioreactors. After studying batch, fed‐batch and continuous processes, continuous culture in a stirred tank bioreactor was found best in terms of regular enzyme production, exceptionally good operational stability and good fitting of the results to mathematical models. Copyright © 2009 Society of Chemical Industry     

1,13-十三碳二羧酸发酵工艺的研究

以热带假丝酵母(Candidatropicalis)为菌种发酵生产1,13 十三碳二羧酸(DCl3)是现阶段最经济的方法。通过对接种量、补碱工艺、发酵级数和空气流量的优化以及采取中间补加正十三碳烷烃(C13)、延长发酵周期等措施,确定了最佳的DC13发酵工艺,15m3发酵DC13的产量达到850kg,主要原材料正十三碳烷烃的消耗下降了11 6%。     

Antibodies directed against a yeast carboxyl-terminal peroxisomal targeting signal specifically recognize peroxisomal proteins from various yeasts.

The carboxyl-terminal tripeptide Ala-Lys-Ile is essential for targeting Candida tropicalis trifunctional enzyme (hydratase-dehydrogenase-epimerase) to peroxisomes of both Candida albicans and Saccharomyces cerevisiae (Aitchison,J.D., Murray, W.W. and Rachubinski, R. A. (1991).J. Biol. Chem. 266, 23197-23203). We investigated the possibility that this tripeptide may act as a general peroxisomal targeting signal (PTS) for other proteins in the yeasts C. tropicalis, C. albicans, Yarrowia lipolytica and S. cerevisiae, and in rat liver. Anti-AKI antibodies raised against the carboxyl-terminal 12 amino acids of trifunctional enzyme were used to search for this PTS in proteins of these yeasts and of rat liver. The anti-AKI antibodies reacted exclusively with multiple peroxisomal proteins from the yeasts C. tropicalis, C. albicans and Y. lipolytica. There was a weak reaction of the antibodies with one peroxisomal protein from S. cerevisiae and no reaction with peroxisomal proteins from rat liver. Antibodies directed against a synthetic peptide containing a carboxyl-terminal Ser-Lys-Leu PTS (Gould, S. J., Krisans, S., Keller, G.-A. and Subramani, S. (1990). J. Cell Biol. 110,27-34) reacted with multiple peroxisomal proteins of rat liver and with peroxisomal proteins of yeast distinct from those identified with anti-AKI antibodies. These results provide evidence that several peroxisomal proteins of different yeasts contain a PTS antigenically similar to that of C. tropicalis trifunctional enzyme and that this signal is absent from peroxisomal proteins from at least one mammalian system, rat liver.     

Scarcity of ars sequences isolated in a morphogenesis mutant of the yeast Yarrowia lipolytica

Previous attempts is isolate autonomously replicating sequences (ars) from the dimorphic yeast Yarrowia lipolytica have been unsuccessful. We isolated a Fil- mutant unable to produce hyphae and growing only in a yeast form to facilitate ars isolation. This mutant was transformed with a Y. lipolytica DNA bank and several unstable clones were obtained. Extrachromosomal plasmids were evidenced in yeast, recovered in Escherichia coli and characterized by restriction mapping. They were able to retransform Fil- and Fil+ yeast strains at high frequency and transformants displayed a slightly unstable phenotype. The detailed analysis of the plasmids showed that only two different ars sequences had been isolated, each of them corresponding to a unique sequence in the Y. lipolytica genome. We concluded that functional ars sequences that can be cloned on plasmids are rare in this yeast.     

Cell surface characterization of Yarrowia lipolytica IMUFRJ 50682

In the present work, the surface characteristics of a wild-type strain of Yarrowia lipolytica (IMUFRJ50682) were investigated. Six different methods to characterize cell surfaces--adhesion to polystyrene; hydrophobic interaction chromatography (HIC); microbial adhesion to solvents (MATS) test; zeta potential; microbial adhesion to hydrocarbons (MATH) test; and contact angle measurement (CAM)--were employed to explain the cell surface behaviour of Y. lipolytica (IMUFRJ50682). This Y. lipolytica strain presents significant differences at the cell surface compared with another Y. lipolytica strain (W29) previously reported in the literature. The main difference is related to the higher cell adhesion to non-polar solvents. The proteins present on the cell wall of Y. lipolytica IMUFRJ50682 seem to play an important role in these particular surface characteristics because of the consistent reduction of this yeast hydrophobic character after the action of pronase on its cell wall.     

两阶段调控葡萄糖质量浓度强化赤藓糖醇发酵的研究

该研究在5 L发酵罐水平上研究了不同初始葡萄糖质量浓度对解脂耶氏酵母（Yarrowia lipolytica）JZ-204生长和发酵产赤藓糖醇的影响。结果表明,100 g/L初始葡萄糖质量浓度有利于菌体生长,高初始葡萄糖质量浓度（300 g/L和400 g/L）有利于赤藓糖醇合成。基于此,提出两阶段葡萄糖质量浓度调控策略,即0 h时以初始葡萄糖质量浓度为100 g/L,22 h后通过补加葡萄糖使总糖量达300 g/L进行发酵。结果表明,与分批发酵相比（100 g/L、200 g/L、300 g/L、400 g/L）,采用该调控策略,赤藓糖醇产量达到最高水平92.66 g/L,分别比分批发酵提高了1 347.81%、84.54%、14.66%、7.57%;生产强度达到最高的0.48 g/（L·h）,分别比分批发酵提高了300%、37.14%、29.73%、20.00%。该调控策略为赤藓糖醇的高效发酵合成提供参考。